Non-black rubber membranes

ABSTRACT

A roofing membrane comprising an olefinic rubber; and from about 20 to about 250 parts by weight of a silica filler per 100 parts by weight rubber; wherein the silica filler is chemically coupled to the olefinic rubber; and wherein the roofing membrane is non-black.

This application is a divisional application of U.S. Non-Provisionalapplication Ser. No. 13/287,417, filed Nov. 2, 2011, which is adivisional application of U.S. Ser. No. 12/389,145, filed on Feb. 19,2009, which issued on Feb. 5, 2013 as U.S. Pat. No. 8,367,760, whichclaims the benefit of U.S. Provisional Application Ser. No. 61/029,777,filed on Feb. 19, 2008, all of which are incorporated herein byreference.

FIELD OF THE INVENTION

One or more embodiments of the present invention relate generally tonon-black rubber sheeting materials. Certain embodiments relate tosilica-filled olefinic rubber membranes, including EPDM membranes, foruse in roofing applications.

BACKGROUND OF THE INVENTION

Ethylene-propylene-diene terpolymer (EPDM) is extensively used in avariety of applications. For example, it is particularly useful as apolymeric sheeting material, which, because of its excellent physicalproperties, flexibility, weathering resistance, low temperatureproperties and heat aging resistance, has gained acceptance as a roofingmembrane for covering industrial and commercial roofs. These roofingmembranes are typically applied to the roof surface in a vulcanized orcured state and serve as an effective barrier to prevent the penetrationof moisture to the covered roof.

Traditional EPDM roofing membranes are generally black or very dark incolor, and are typically prepared by compounding the base polymer ofEPDM with one or more carbon black fillers, processing oil, and otherdesired ingredients such as plasticizers, antidegradants,adhesive-enhancing promoters, etc., in a suitable mixer, and calenderingthe resulting compound into the desired thickness. The roofing membranemay also be cured by vulcanizing the resultant sheet in the presence ofone or more vulcanizing agents and/or compatible vulcanizingaccelerators. Vulcanizing agents such as sulfur or sulfur-donatingcompounds such as mercaptans are typically used, although vulcanizationand curing may be done using other agents or in the presence of othercompounds.

While black or dark-colored EPDM membranes have been used for decades ascommercial single-ply roofing membranes, such membranes are known toabsorb sunlight and become hot. This has lead to various environmentaland energy concerns. In recent years, great efforts have been madetoward producing white and/or other non-black EPDM membranes that aremore environmentally friendly and more energy efficient. Various mineralfillers such as clay, talc, silicas, mica, calcium carbonate, and thelike, in various combinations, have been added to various roofingmembrane formulations to improve energy absorption characteristics.

One particular type of non-black mineral filler that has been used incombination with various clay fillers in non-black EPDM membranesincludes silicas. It is known that silica, when used in combination withvarious clay mineral fillers as an EPDM membrane, can improve certainphysical properties such as abrasion resistance and tear resistance.However, silicas, by themselves, do not provide effective reinforcementof the rubber membranes such as carbon black does in black EPDMmembranes. Thus, there remains a need for a silica-filled olefinicmembrane with improved performance and processing properties beyondthose already known.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a roofingmembrane comprising an olefinic rubber and from about 20 to about 250parts by weight of a silica filler per 100 parts by weight rubber,wherein the silica filler is chemically coupled to the olefinic rubberand wherein the roofing membrane is non-black.

One or more embodiments of the present invention further provide amethod for improving the reinforcement properties of a non-blacksilica-filled olefinic roofing membrane comprising providing a mixtureof an olefinic rubber and from about 20 to about 250 parts by weight ofa silica filler per 100 parts by weight rubber, adding a silane couplingagent compatible with the olefinic rubber and the silica filler suchthat the olefinic rubber is chemically linked to the silica filler.

One or more embodiments of the present invention further provide avulcanizable composition suitable for use in the production of a roofingmembrane, the composition comprising the reaction product of an olefinicrubber from about 20 to about 250 parts by weight of a silica filler per100 parts by weight rubber; and from about 0.1 to about 5 parts byweight of a silane coupling agent per 100 parts by weight rubber,wherein the silane coupling agent is compatible with both the olefinicrubber and the silica filler, such that the olefinic rubber ischemically coupled to the silica filler.

One or more embodiments of the present invention further provide amethod for the production of a roofing membrane comprising mixing aolefinic rubber, a silica filler, and a silane coupling agent in amasterbatch, wherein the silica filler reacts with the silane couplingagent to form an uncured compound, calendering the uncured compound intoone or more layers to form a sheet, and curing the calendered uncuredcompound such that the olefinic rubber is chemically coupled to thesilica filler.

One or more embodiments of the present invention still further provide alaminate membrane comprising a first layer including a cured elastomericolefinic copolymer and silica, where at least a portion of the silica iscoupled to the elastomeric olefinic copolymer a second layer includingcured elastomeric olefinic copolymer and carbon black, and optionally ascrim fabric.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

One or more embodiments of the present invention are directed towardnon-black roofing membranes that include cured rubber (e.g. EPDM) andnon-black reinforcing filler (e.g. silica), wherein at least a portionof the rubber has been chemically coupled to at least a portion of thenon-black reinforcing filler. In one or more embodiments, a silanecoupling agent is employed to effect the coupling between the non-blackreinforcing filler and the rubber. Thus, certain embodiments include avulcanizable composition including not only a vulcanizable polymer and anon-black reinforcing filler, but also a coupling agent. An uncuredsheet can be formed from this composition and cured such that, uponcuring, the rubber is chemically coupled to the filler. In one or moreembodiments, a silane coupling agent acts to link the rubber and asilica filler together in such a way as to produce cured compositioncharacterized by advantageous physical properties. Also, in one or moreembodiments, the introduction of a silane coupling agent providestechnological advantage during processing of the vulcanizablecomposition employed in making the membranes.

In one or more embodiments, the membranes of the present invention aremonolithic membranes. These membranes include those where thecomposition of the membrane (excluding any optional scrim) ishomogeneous throughout the thickness of the membrane. In one or moreembodiments, these monolithic membranes derive from a single calenderedsheet. In one or more embodiments, these monolithic membranes mayoptionally include a scrim such as a reinforcing scrim. Membranesincluding a scrim fabric may be referred to as composite membranes.

In other embodiments, the membranes of the present invention arelaminate membranes including at least non-black layer prepared from anon-black rubber formulation as described herein. In one or moreembodiments, these laminate membranes include at least one layerincluding carbon black as a filler. In certain embodiments, thesebilaminate membranes may be composites and include scrim.

In either event, the membranes of the present invention include at leastone non-black polymeric layer that derives from the non-blackvulcanizable compositions described herein.

The membranes of the present invention (or at least one non-black layerof the membranes of the present invention) are prepared from non-blackvulcanizable compositions of matter that include a rubber, a non-blackreinforcing filler, a curative, and a coupling agent. They may be simplyreferred to as vulcanizable compositions. Optional ingredients may alsobe added.

In one or more embodiments, useful rubber includes elastomeric olefiniccopolymer rubber, which may simply be referred to as olefinic rubber,olefinic copolymer, or simply rubber. In one or more embodiments, usefulolefinic rubber includes that rubber that is capable of being cured orcrosslinked with sulfur or sulfur-based cure systems.

In one or more embodiments, the olefinic copolymer is a terpolyer thatincludes mer units that derive from ethylene, α-olefin, and optionallydiene monomer. Useful α-olefins include propylene. In one or moreembodiments, the diene monomer may include dicyclopentadiene,alkyldicyclopentadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene,1,4-heptadiene, 2-methyl-1,5-hexadiene, cyclooctadiene, 1,4-octadiene,1,7-octadiene, 5-ethylidene-2-norbornene, 5-n-propylidene-2-norbornene,5-(2-methyl-2-butenyl)-2-norbornene, and mixtures thereof. Olefinicterpolymers and methods for their manufacture are known as disclosed atU.S. Pat. No. 3,280,082, which is incorporated herein by reference. Forpurposes of this specification, elastomeric olefinic copolymers may bereferred to as elastomeric olefinic terpolymers, terpolymers, or simplyEPDM.

In one or more embodiments, the terpolymer may include at least 55weight percent, in other embodiments at least 60 weight percent, inother embodiments at least 62 weight percent, and in other embodimentsat least 64 weight percent mer units deriving from ethylene; in these orother embodiments, the elastomeric terpolymer may include less thanabout 73 weight percent, in other embodiments less than about 70 weightpercent, and in other embodiments less than about 69 weight percent, merunits deriving from ethylene.

In one or more embodiments, the elastomeric terpolymer may include atleast 1 percent by weight, in other embodiments at least 1.5 percent byweight, in other embodiments at least 2 weight percent, in otherembodiments at least 2.4 weight percent, mer units deriving from dienemonomer; in these or other embodiments, the elastomeric terpolymer mayinclude less than about 4 weight percent, and in other embodiments lessthan about 3.2 weight percent, mer units deriving from diene monomer. Inone or more embodiments, the balance of the mer units derive frompropylene or other α-olefins. In particular embodiments of the presentinvention, the use of a silane coupling agent may advantageously providefor the use of terpolymer rubber having relatively low amounts of diene;for example, terpolymer rubber including from about 1 to about 2percent, or in other embodiments from about 1.3 to about 1.7 percent,mer units deriving from diene monomer may be used.

In one or more embodiments, the useful elastomeric olefinic terpolymer(EPDM) may be characterized by a Mooney Viscosity (ML₁₊₄@125° C.) ofabout 35 to about 70, and in other embodiments from about 50 to about70.

Useful EPDM varieties are commercially available. Examples includeRoyalene® 512, which has a Mooney Viscosity (ML₁₊₄@125° C.) range of 52to 67, and an ethylene to propylene ratio of 68/32. Other example EPDMssuitable for the present invention include, but are not limited to,Royalene® 512 and Royalene® 502.

In one or more embodiments, the EPDM membrane is cured or crosslinked.In one or more embodiments, the EPDM membrane is cured at a temperatureof about 160° C. In another embodiment, the EPDM membrane may be curedin an autoclave in the presence of steam and pressure.

EPDM can be cured by using numerous techniques such as those that employsulfur cure systems, peroxide cure systems, and quinone-type curesystems. The sulfur cure systems may be employed in combination withvulcanizing accelerators. Useful accelerators include thioureas such asethylene thiourea, N,N-dibutylthiourea, N,N-diethylthiourea and thelike; thiuram monosulfides and disulfides such as tetramethylthiurammonosulfide (TMTMS), tetrabutylthiuram disulfide (TBTDS),tetramethylthiuram disulfide (TMTDS), tetraethylthiuram monosulfide(TETMS), dipentamethylenethiuram hexasulfide (DPTH) and the like;benzothiazole sulfenamides such as N-oxydiethylene-2-benzothiazolesulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide,N,N-diisopropyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazolesulfenamide (TBBS) (available as Delac® NS from Chemtura, Middlebury,Conn.) and the like; other thiazole accelerators such as2-mercaptobenzothiazole (MBT), benzothiazyl disulfide (MBTS),N,N-diphenylguanidine, N,N-di-(2-methylphenyl)-guanidine,2-(morpholinodithio)benzothiazole disulfide, zinc2-mercaptobenzothiazole and the like; dithiocarbamates such as telluriumdiethyldithiocarbamate, copper dimethyldithiocarbamate, bismuthdimethyldithiocarbamate, cadmium diethyldithiocarbamate, leaddimethyldithiocarbamate, sodium butyldithiocarbamate, zincdiethyldithiocarbamate, zinc dimethyldithiocarbamate, zincdibutyldithiocarbamate (ZDBDC) and mixtures thereof. Sulfur donor-typeaccelerators (e.g. di-morpholino disulfide and alkyl phenol disulfide)may be used in place of elemental sulfur or in conjunction withelemental sulfur if desired.

Examples of suitable peroxides that can be used as curing agents orco-curing agents include alpha-cumyl hydroperoxide, methylethylketoneperoxide, hydrogen peroxide, acetylacetone peroxide, t-butylhydroperoxide, t-butyl peroxybenzoate, 2,5-bis(t-butylperoxy)-2,5-dimethylhexene, lauryl peroxide, benzoyl peroxide,2,4-dichlorobenzoyl peroxide, dibenzoyl peroxide,bis(p-monomethylene-benzoyl) peroxide, bis(p-nitrobenzoye peroxide,phenylacetyl peroxide, and mixtures thereof.

Examples of inorganic peroxides which can be used as co-curing agentswith p-quinone dioxime include lead peroxide, zinc peroxide, bariumperoxide, copper peroxide, potassium peroxide, silver peroxide, sodiumperoxide, calcium peroxide, metallic peroxyborates, peroxychromates,peroxydicarbonates, peroxydiphosphates, peroxydisulfates,peroxygermanates, peroxymolybdates, peroxynitrates, magnesium peroxide,sodium pyrophosphate peroxide, and mixtures thereof.

Examples of polysulfide activators for the quinone-type co-curing agentsinclude calcium polysulfide, sodium polysulfide, as well as organicpolysulfides having the general formula R—(S)_(x)—R, wherein R is ahydrocarbon group and x is a number from 2-4. Examples of organicpolysulfides are disclosed in U.S. Pat. No. 2,619,481, which isincorporated herein by reference.

Conventional radiation equipment and techniques can also be employed inthe practice of this invention. Suitable ionizing crosslinking promotersthat can be used include: liquid high-vinyl 1,2-polybutadiene resinscontaining 90 percent 1,2-vinyl content; Sartomer SR-206 (ethyleneglycol dimethacrylate), Di-Cup R(dicumyl peroxide, about 98 percentactive), and Pental A (pentaerythritol resin prepared from tall oil).These chemical additives are preferably compatible with the otheringredients in the composition, they may also function to reduce thedosage of ionizing radiation needed to obtain the desired level ofcrosslinking.

Sulfur and sulfur-containing cure systems may be used, and may also beused with an accelerator. Suitable amounts of sulfur can be readilydetermined by those skilled in the art. In one or more embodimentsroughly about 1 part by weight (pbw) sulfur per 100 parts by weightrubber (phr) may be used. The amount of accelerator can also be readilydetermined by those skilled in the art.

In one or more embodiments, non-black reinforcing fillers includemineral fillers that are characterized by a particle size (averagediameter or cross-section) of less than 10 microns, in other embodimentsless than 5 microns, and in other embodiments less than 1 micron. Inthese or other embodiments, these fillers are characterized by aparticle size of at least 10 nanometers, in other embodiments at least50 nanometers, and in other embodiments at least 100 nanometers.

In one or more embodiments, the non-black reinforcing fillers include amoiety or group that is capable of reacting with a silane moiety orgroups of a silane coupling agent. In one or more embodiments, thenon-black reinforcing filler includes one or more hydroxyl groups on thesurface of the filler particle.

In one or more embodiments, a single type of reinforcing non-blackfiller may be employed, and in other embodiments two or more reinforcingnon-black fillers may be used in conjunction. In one or moreembodiments, one or more reinforcing fillers may be employed inconjunction with one or more non-reinforcing fillers. Thenon-reinforcing fillers may include non-black mineral fillers that donot include groups or moieties that will react with a silane and/or arelarger in particle size than the reinforcing fillers.

In one or more embodiments, silica is employed as the non-blackreinforcing filler. In one or more embodiments, silica filler isemployed alone. In other embodiments, silica filler is included withTiO₂. In other embodiments, silica filler is included along with othermineral fillers that do not substantially reinforce the composition.

In one or more embodiments, useful forms of silica (silicon dioxide)include crystalline and amorphous silica. The crystalline form of silicaincludes quartz, tridymite and cristobalite. Amorphous silica may occurwhen the silicon and oxygen atoms are arranged in an irregular form asidentified by X-ray diffraction. In one or more embodiments, the silicais a precipitated silica. In these or other embodiments, fumed silica isemployed.

Commercially available forms are available from PPG Industries, Inc.(Monroeville, Pa.), Degussa Corporation (Parsippany, N.J.) and J.M.Huber Corporation (Atlanta, Ga.). One useful commercial product isRubbersil® RS-150, which is characterized by a BET surface area of 150m²/g, tapped density of 230 g/liter, pH (5% in water suspension) of 7,SiO2 content of 98%, Na2SO4 content of 2%, and Al2O3 content of 0.2%. Inat least one embodiment, silica filler may be used without any othermineral fillers.

In one or more embodiments, other non-black reinforcing fillers includemagnesium hydroxide. In yet other embodiments, non-black reinforcingfillers include aluminum trihydrate.

In one or more embodiments, titanium dioxides may be optionallyincluded. Useful titanium dioxides include rutile forms of titaniumdioxide. One useful commercial product is TiPure® R-960 (DuPont), whichis a fine, white powder having a specific gravity of 3.90. Anothersuitable titanium dioxide product is CR-800 (TRONOX), which is believedto be characterized by a titanium dioxide content of about 96% and aspecific gravity of about 3.8 to about 4.1.

In one or more embodiments, talc may optionally be included. Useful talcinclude hydrated magnesium silicate. In one or more embodiments, talccan be represented by the formulae Mg₃Si₄O₁₀(OH)₂ or 3MgO.4SiO₂.H₂O.Exemplary forms of talc include talcum, soapstone, steatite, cerolite,magnesium talc, steatite-massive, and mixtures thereof. Talc filler maycontain various other minerals such as dolomite, chlorite, quartz, andthe like. Talc used as filler may also exhibit characteristics such ashydrophobicity, organophilicity, non-polarity, and chemically inertness.A representative commercially available talc is Talc 9107, which isavailable from Polar Minerals (Mt. Vernon, Ind.), which is non-abrasive,chemically inert, has a specific gravity of about 2.8, a pH of about8.7, a refractive index of about 1.57 at 23° C., and a moisture contentof less than about 0.3 weight percent.

Another suitable talc is Mistron® Vapor Talc, which is available fromLuzenac America (Centennial, Colo.). Mistron® Vapor Talc is a soft,ultra-fine, white platy powder having a specific gravity of 2.75, amedian particle size of 1.7 microns, an average surface area of 18 m²/g,and a bulk density (tapped) of 20 lbs/ft³. Other talcs commerciallyavailable from Luzenac America (Centennial, Colo.), include Vertal MB,and Silverline 002. In one embodiment, talc is characterized as a platy,chemically inert filler having a specific gravity of from about 2.6 toabout 2.8, a pH of about 7, and a moisture content of less than about0.5 weight percent.

While, in one or more embodiments, clays may be used, in otherembodiments, the present invention is devoid of the use of clays of alltypes. Where clays are used, useful clays include hydrated aluminumsilicates. In one or more embodiments, useful clays can be representedby the formula Al₂O₃SiO₂.XH₂O. Exemplary forms of clay includekaolinite, montmorillonite, atapulgite, illite, bentonite, halloysite,and mixtures thereof. In one embodiment, the clay is represented by theformula Al₂O₃SiO₂.3H₂O. In another embodiment, the clay is representedby the formula Al₂O₃SiO₂.2H₂O. In a preferred embodiment, the clay has apH of about 7.0.

In one or more embodiments, various forms or grades of clays may beemployed. Exemplary forms or grades of clay include air-floated clays,water-washed clays, calcined clays, and chemically modified (surfacetreated) clays. In other embodiments, untreated clays may be used.

Air-floated clays include hard and soft clays. In one or moreembodiments, hard clays include those characterized as having a lowermedian particle size distribution, and higher surface area than softclays. In one or more embodiments, soft clays include thosecharacterized by having a higher median particle size distribution andlower surface area than hard clays. Hard and soft clays are disclosed inU.S. Pat. Nos. 5,468,550, and 5,854,327, which are incorporated hereinby reference.

In one embodiment, the air-floated clays used have a pH of from about4.0 to about 8.0, and in another embodiment, the pH is about neutral.Useful airfloated clays have an average particle size of less than about2 microns. Typical airfloated clays have a specific gravity of around2.6 g/cc.

Airfloated clays, both hard and soft, are available through varioussources. Available from Unimin Corporation (New Canaan, Conn.) isSnobrite™ AF, which is an airfloated hard clay having a pH of about 5.5to 7.5, a median particle size of about 1 micron, and a specific gravityof about 2.6 g/cc. Available from Kentucky-Tennessee Clay Company(Mayfield, Ky.) is Paragon, which has a pH of about 4.5 to 5.5, a medianparticle size of about 1 micron, and a specific gravity of about 2.6g/cc, and Tennessee Clay No. 6, an airfloated hard clay with a pH offrom about 5.5 to 6.5, a median particle size of about 1.0 micron, and aspecific gravity of about 2.6. A soft airfloated clay from UniminCorporation (New Canaan, Conn.) is Hi White R®, which has a pH of about6.25, a median particle size of less than about 1 micron, and a specificgravity of about 2.6 g/cc, Alumex, and Suprex, all airfloated softclays. Available from J.M. Huber Corporation (Atlanta, Ga.) is Barden R,and LGB, which are both airfloated hard clays, and K-78, an airfloatedsoft clay. Available from R.T. Vanderbilt Company (Norwalk, Conn.) isMcNamee Clay, which is an airfloated soft clay having a pH of about 5.0to 7.5, a median particle size of about 1 micron and a specific gravityof about 2.6 g/cc.

Water washed clays include those clays that are more closely controlledfor particle size by the water fractionation process. This processpermits the production of clays within controlled particle size ranges.In one embodiment, the average particle size of the clay is less thanabout 2 microns in diameter. In another embodiment, the pH of the clayis about 7. Available from J.M. Huber Corporation (Atlanta, Ga.) arewater washed clays such as Polyfil® DL, Polyfil® F, Polyfil® FB,Polyfil® HG-90, Polyfil® K and Polyfil® XB. In one embodiment, a waterwashed kaolin clay includes hydrated aluminum silicate, which has a pHof from about 6 to about 7.5, and a specific gravity of about 2.6 g/cc.

Calcined clays include those that result from the removal of watercontained in clays (clays typically contain about 14 percent water) bycalcination. The amount of bound water removed determines the degree ofcalcination. In one embodiment, the average particle size of the clay isless than about 2 microns in diameter. In another embodiment, the pH ofthe clay is about 7. Available from J.M. Huber Corporation (Atlanta,Ga.) are calcined clays such as Polyfil® 40, Polyfil® 70, and Polyfil®80.

Chemically modified (surface treated) clays include those that havecross-linking ability, which can be imparted to the clay by modifyingthe surface of individual particles with a polyfunctional silanecoupling agent. In one embodiment, the average particle size of the clayis less than about 2 microns in diameter. In another embodiment, the pHof the clay is about 7. Available from J.M. Huber Corporation (Atlanta,Ga.) are Nucap® 100 G, Nucap® 200, Nucap® 190, Nucap® 290, Nulok® 321,Nulok® 390, and Polyfil® 368.

In one or more embodiments, coupling agents include those compounds thatcan chemically link the rubber to the non-black reinforcing filler. Inone or more embodiments, the coupling agents include a silane group ormoiety that is believed to react with a hydroxyl group on the non-blackreinforcing filler and chemically bond thereto. Inasmuch as silicaincludes hydroxyl groups that will react with silane groups on thecoupling agent, the coupling agents may be referred to as silicacoupling. In other embodiments, the coupling agents may be referred toas silane coupling agents. Useful silica coupling agents are disclosedin U.S. Pat. Nos. 3,842,111, 3,873,489, 3,978,103, 3,997,581, 4,002,594,5,580,919, 5,583,245, 5,663,396, 5,674,932, 5,684,171, 5,684,172,5,696,197, 6,608,145, and 6,667,362, the disclosures of which areincorporated herein by reference.

In one or more embodiments, the silane coupling agent may be anorganosilane. In one or more embodiments, the silane coupling agent maybe a hindered silane. In yet one or more other embodiments, the silanecoupling agent may be a mercapto silane. In still one or more otherembodiments, the silane coupling agent may be is a bi-functionalsulfur-silane having a blocked mercapto group. In still one or moreother embodiments, the silane coupling agents may include an alkoxysilylor silyl halide functional group.

In one or more embodiments, the use of hindered silane coupling agentsprovides for several advantages. For example, the processing propertiesand the physical properties of the resultant compound have, in certainembodiments, proven to be advantageous. For example, silica-filled EPDMmembranes have been shown to have increased physical properties, such ashigher modulus, higher tensile strength and improved tear resistance, ascompared to silica-filled EPDM membranes prepared without a silanecoupling agent. Furthermore, processing properties, such as increasedscorch safety and decreased compound viscosity (i.e., softer compoundsrequiring less energy to break down stocks before processing orcalendering) have been found. Also, the reduction in viscosity of themembrane due to the use of the silane coupling agent allows for higherloading of fillers and for higher molecular weight polymers to be usedwithout sacrificing compound processing properties. Finally, it has beenfound that membranes having employed the silane coupling agent in theproduction of the mineral (silica)-filled EPDM compounds require lesstime to cure to have equal or better physical properties.

Examples of silane coupling agents includebis(trialkoxysilylorgano)polysulfides, mercaptosilanes, and blockedmercaptosilanes. Bis(trialkoxysilylorgano)polysulfides includebis(trialkoxysilylorgano)disulfides andbis(trialkoxysilylorgano)tetrasulfides. Examples ofbis(trialkoxysilylorgano)disulfides include3,3′-bis(triethoxysilylpropyl)disulfide,3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(tributoxysilylpropyl)disulfide,3,3′-bis(tri-t-butoxysilylpropyl)disulfide,3,3′-bis(trihexoxysilylpropyl)disulfide,2,2′-bis(dimethylmethoxysilylethyl)disulfide,3,3′-bis(diphenylcyclohexoxysilylpropyl)disulfide,3,3′-bis(ethyl-di-sec-butoxysilylpropyl)disulfide,3,3′-bis(propyldiethoxysilylpropyl)disulfide,3,3′-bis(triisopropoxysilylpropyl)disulfide,3,3′-bis(dimethoxyphenylsilyl-2-methylpropyl)disulfide, and mixturesthereof.

Examples of bis(trialkoxysilylorgano)tetrasulfide silica coupling agentsinclude bis(3-triethoxysilylpropyl)tetrasulfide,bis(2-triethoxysilylethyl)tetrasufide,bis(3-trimethoxysilylpropyl)tetrasulfide,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,2-triethoxysilyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-trimethoxysilylpropyl-benzothiazole tetrasulfide,3-triethoxysilylpropylbenzothiazole tetrasulfide, and mixtures thereof.Bis(3-triethoxysilylpropyl)tetrasulfide is sold commercially as Si69 byDegussa.

Mercaptosilanes include compounds represented by the formula

where R⁸ is a divalent organic group or a bond, R⁹ is a halogen atom oran alkoxy group, and each R¹⁰ is independently a halogen, an alkoxygroup, or a monovalent organic group. In one embodiment, at least one ofR⁹ and R¹⁰ is an alkoxy group, and in another embodiment, R⁹ and eachR¹⁰ is an alkoxy group. In certain embodiments, the alkoxy group hasfrom 1 to 4 carbon atoms. In certain embodiments, the divalent organicgroup is an alkylene group containing from 1 to about 4 carbon atoms. Incertain embodiments, the halogen is chlorine, bromine, iodine, orfluorine, and in one embodiment, the halogen is chlorine.

Examples of mercaptosilanes include 1-mercaptomethyltriethoxysilane,2-mercaptoethyltriethoxysilane, 3-mercaptopropyltriethoxysilane,3-mercaptopropylmethyldiethoxysilane, 2-mercaptoethyltripropoxysilane,18-mercaptooctadecyldiethoxychlorosilane, and mixtures thereof.

In one or more embodiments, mercaptosilanes also include blockedmercaptosilane compounds. In one or more embodiments, these blockedcompounds can be used in conjunction with a deblocking agent.Advantageously, blocked mercaptosilanes do not provide an unpleasantodor, unlike the mercaptosilanes above. Blocked mercaptosilanes mayinclude sulfur-containing silanes where a sulfur atom is bonded to asilyl group, perhaps through a linking moiety, and the sulfur atom isalso bonded to a blocking group. In one or more embodiments, duringprocessing, the blocking group can be removed to form a mercaptosilanethat is capable of acting as a coupling agent. An example of a simpleblocked mercaptosilane can be represented by the formula

where R⁸, R⁹ and R¹⁰ are as described above, and R¹¹ is a blocking groupthat will come off during processing leaving the S free to react withthe polymer. In one embodiment, R¹¹ contains an unsaturated heteroatomor carbon chemically bound directly to S via a single bond, and isoptionally substituted with one or more carboxylate ester or carboxylicacid functional groups. In another embodiment, R¹¹ is a carboxy grouphaving from 1 to about 18 carbon atoms. Blocked mercaptosilanes arefurther described in U.S. Pat. Nos. 6,579,949 and 6,683,135, which areincorporated herein by reference.

Examples of blocked mercaptosilanes include 2-triethoxysilyl-1-ethylthioacetate, 2-trimethoxysilyl-1-ethyl thioacetate,2-(methyldimethoxysilyl)-1-ethyl thioacetate, 3-trimethoxysilyl-1-propylthioacetate, triethoxysilylmethyl thioacetate, trimethoxysilylmethylthioacetate, triisopropoxysilylmethyl thioacetate,methyldiethoxysilylmethyl thioacetate, methyldimethoxysilylmethylthioacetate, methyldiisopropoxysilylmethyl thioacetate,dimethylethoxysilylmethyl thioacetate, dimethylmethoxysilylmethylthioacetate, dimethylisopropoxysilylmethyl thioacetate,2-triisopropoxysilyl-1-ethyl thioacetate,2-(methyldiethoxysilyl)-1-ethyl thioacetate,2-(methyldiisopropoxysilyl)-1-ethyl thioacetate,2-(dimethylethoxysilyl)-1-ethyl thioacetate,2-(dimethylmethoxysilyl)-1-ethyl thioacetate,2-(dimethylisopropoxysilyl)-1-ethyl thioacetate,3-triethoxysilyl-1-propyl thioacetate, 3-triisopropoxysilyl-1-propylthioacetate, 3-methyldiethoxysilyl-1-propyl thioacetate,3-methyldimethoxysilyl-1-propyl thioacetate,3-methyldiisopropoxysilyl-1-propyl thioacetate,1-(2-triethoxysilyl-1-ethyl)-4-thio acetylcyclohexane,1-(2-triethoxysilyl-1-ethyl)-3-thioacetylcyclohexane,2-triethoxysilyl-5-thioacetylnorbornene,2-triethoxysilyl-4-thioacetylnorbornene,2-(2-triethoxysilyl-1-ethyl)-5-thioacetylnorbornene,2-(2-triethoxysilyl-1-ethyl)-4-thioacetylnorbornene,1-(1-oxo-2-thio-5-triethoxysilylpenyl)benzoic acid,6-triethoxysilyl-1-hexyl thioacetate, 1-triethoxysilyl-5-hexylthioacetate, 8-triethoxysilyl-1-octyl thioacetate,1-triethoxysilyl-7-octyl thioacetate, 6-triethoxysilyl-1-hexylthioacetate, 1-triethoxysilyl-5-octyl thioacetate,8-trimethoxysilyl-1-octyl thioacetate, 1-trimethoxysilyl-7-octylthioacetate, 10-triethoxysilyl-1-decyl thioacetate,1-triethoxysilyl-9-decyl thioacetate, 1-triethoxysilyl-2-butylthioacetate, 1-triethoxysilyl-3-butyl thioacetate,1-triethoxysilyl-3-methyl-2-butyl thioacetate,1-triethoxysilyl-3-methyl-3-butyl thioacetate,3-trimethoxysilyl-1-propyl thiooctanoate, 3-triethoxysilyl-1-propylthiopalmitate, 3-triethoxysilyl-1-propyl thiooctanoate,3-triethoxysilyl-1-propyl thiobenzoate, 3-triethoxysilyl-1-propylthio-2-ethylhexanoate, 3-methyldiacetoxysilyl-1-propyl thioacetate,3-triacetoxysilyl-1-propyl thioacetate, 2-methyldiacetoxysilyl-1-ethylthioacetate, 2-triacetoxysilyl-1-ethyl thioacetate,1-methyldiacetoxysilyl-1-ethyl thioacetate, 1-triacetoxysilyl-1-ethylthioacetate, tris-(3-triethoxysilyl-1-propyl)trithiophosphate,bis-(3-triethoxysilyl-1-propyl)methyldithiophosphonate,bis-(3-triethoxysilyl-1-propyl)ethyldithiophosphonate,3-triethoxysilyl-1-propyldimethylthiophosphinate,3-triethoxysilyl-1-propyldiethylthiophosphinate,tris-(3-triethoxysilyl-1-propyl)tetrathiophosphate,bis-(3-triethoxysilyl-1-propyl)methyltrithiophosphonate,bis-(3-triethoxysilyl-1-propyl)ethyltrithiophosphonate,3-triethoxysilyl-1-propyldimethyldithiophosphinate,3-triethoxysilyl-1-propyldiethyldithiophosphinate,tris-(3-methyldimethoxysilyl-1-propyetrithiophosphate,bis-(3-methyldimethoxysilyl-1-propyl)methyldithiophosphonate,bis-(3-methyldimethoxysilyl-1-propyl)ethyldithiophosphonate,3-methyldimethoxysilyl-1-propyldimethylthiophosphinate,3-methyldimethoxysilyl-1-propyldiethylthiophosphinate,3-triethoxysilyl-1-propylmethylthiosulphate,3-triethoxysilyl-1-propylmethanethiosulphonate,3-triethoxysilyl-1-propylethanethiosulphonate,3-triethoxysilyl-1-propylbenzenethiosulphonate,3-triethoxysilyl-1-propyltoluenethiosulphonate,3-triethoxysilyl-1-propylnaphthalenethiosulphonate,3-triethoxysilyl-1-propylxylenethiosulphonate,triethoxysilylmethylmethylthiosulphate,triethoxysilylmethylmethanethiosulphonate,triethoxysilylmethylethanethiosulphonate,triethoxysilylmethylbenzenethiosulphonate,triethoxysilylmethyltoluenethiosulphonate,triethoxysilylmethylnaphthalenethiosulphonate, andtriethoxysilylmethylxylenethiosulphonate. Blocked mercaptosilanes arecommercially available from GE Silicones-OSi Specialties as NXT®silanes. A useful blocked silane is Deolink MX (thiocarboxylsilane),manufactured by DOG-Chemie (Hamburg, Germany).

In one or more embodiments, blocked mercaptosilanes are used inconjunction with a deblocking agent. In certain embodiments, deblockingagents can function as a proton source and a blocking group acceptor.When reaction of the mixture to couple the filler to the polymer isdesired, a deblocking agent is added to the mixture to deblock theblocked mercaptosilane. Deblocking agents, which are sometimes referredto as deprotection agents, include N,N′-diphenylguanidine,ethanolamines, ethyleneamines, ethylene glycol, polyethylene glycols,propylene glycol, polypropylene glycols, mixed ethylene-propyleneglycols, alkyl-terminated glycols, glycerol, trimethylol alkanes,pentaerythritol, aniline, phenylene diamines, phenol, catechol,dihydroquinone, resorcinol, aminophenol, 1,3-diaminopropane,1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane,N-(3-aminopropyl)-1,3-propanediamine(3,3′-iminobispropylamine),3-amino-1-propanol, imidazole, benzimidazole, aminobenzimidazole,pyrrole, indole, pyrazole, triazole, benzotriazole, and mixturesthereof. Deblocking is further described in U.S. Pat. Nos. 6,579,949 and6,683,135, which are incorporated herein by reference.

In addition to the foregoing ingredients, the vulcanizable compositionsof this invention may also optionally include processing oils, mica,calcium carbonate, homogenizing agents, flame retardants, zinc oxide,stearic acid, and mixtures thereof. Certain embodiments may besubstantially devoid of any of these constituents.

Processing oils may be used in the present invention. Useful processingoils include paraffinic, naphthenic oils, and mixtures thereof. Theseoils may be halogenated as disclosed in U.S. Pat. No. 6,632,509, whichis incorporated herein by reference. In one or more embodiments, usefulprocessing oils are generally characterized by low sulfur content, lowaromaticity, low volatility, and a flash point of more than about 550°F. In one or more embodiments, these processing oils may be referred toas white oils. In one or more embodiments, useful oils have a sulfurcontent of less than 0.5 weight percent, in other embodiments, less than0.1 weight percent, in other embodiments less than 0.05 weight percent,and in other embodiments less than 0.01 weight percent sulfur. In one ormore embodiments, useful oils have limited unsaturation. In particularembodiments, useful oils have an unsaturation level of less than 3%, inother embodiments less than 1%, in other embodiments less than 0.5%, andin other embodiments less than 0.1%. Useful oils are commerciallyavailable. A useful oil is available under the tradename FHR Ultra 1199.

Mica includes mixtures of sodium and potassium aluminum silicate. Micacan be defined by the chemical formula αΔ2-3(Ω)4O10(Σ)2, where the α ionis potassium, sodium, barium, calcium, cesium, and/or ammonium, the Δion is aluminum, lithium, iron, zinc, chromium, vanadium, titanium,manganese, and/or magnesium, the Ω ion is silicon, aluminum, beryllium,boron, and/or iron (+3), and Σ is oxygen, fluorine, or hydroxide ion.Micas include true micas, brittle micas, and interlayer-deficient micas.True micas include a majority of singularly charged ions (e.g.,potassium and sodium) in the α position. Brittle micas include amajority of doubly charged ions (e.g., calcium or barium) in the αposition. Interlayer-deficient micas include fewer cations in theinterlayer (the layer between the tetrahedral-octahedral-tetrahedrallayers of the crystalline structure) than true or brittle micas.

Examples of true micas include aluminoceladonite (potassium aluminummagnesium iron silicate hydroxide), boromuscovite (potassiumboro-silicate hydroxide), celadonite (potassium iron magnesium silicatehydroxide), chromphyllite (potassium chromium aluminum silicatehydroxide fluoride), ferro-aluminoceladonite (potassium aluminum ironmagnesium silicate hydroxide), ferroceladonite (potassium iron magnesiumsilicate hydroxide), muscovite (potassium aluminum silicate hydroxide),nanpingite (cesium aluminum silicate hydroxide), paragonite (sodiumaluminum silicate hydroxide), roscoelite (potassium vanadium aluminumsilicate hydroxide), tobelite (ammonium aluminum silicate hydroxide),annite (potassium iron aluminum silicate hydroxide), aspidolite (sodiummagnesium aluminum silicate hydroxide), biotite (potassium magnesiumiron aluminum silicate hydroxide fluoride), eastonite (potassiummagnesium aluminum silicate hydroxide), ephesite (sodium lithiumaluminum silicate hydroxide), hendricksite (potassium zinc aluminumsilicate hydroxide), lepidolite (potassium lithium aluminum silicatefluoride hydroxide), masutomilite (potassium lithium aluminum manganesesilicate fluoride), montdorite (potassium iron manganese magnesiumaluminum silicate fluoride), norrishite (potassium lithium manganesesilicate), polylithionite (potassium lithium aluminum silicatefluoride), phlogopite (potassium magnesium aluminum silicate hydroxide),preiswerkite (sodium magnesium aluminum silicate hydroxide),siderophyllite (potassium iron aluminum silicate hydroxide), tainiolite(potassium lithium magnesium silicate fluoride), tetra-ferri-annite(potassium iron silicate hydroxide), tetra-ferriphlogopite (potassiummagnesium iron silicate hydroxide), trilithionite (potassium lithiumaluminum silicate fluoride), zinnwaldite (potassium lithium ironaluminum silicate fluoride hydroxide), and mixtures thereof.

Examples of brittle micas include chernykhite (barium vanadium aluminumsilicate hydroxide), margarite (calcium aluminum silicate hydroxide),anadite (barium potassium iron magnesium aluminum silicate hydroxide),bityite (calcium lithium aluminum beryllium silicate hydroxide),clintonite (calcium magnesium aluminum silicate hydroxide),kinoshitalite (barium magnesium aluminum silicate hydroxide), andmixtures thereof.

Examples of interlayer deficient micas include brammallite (sodiumaluminum silicate hydroxide), glauconite (potassium sodium iron aluminummagnesium silicate hydroxide), illite (potassium aluminum silicatehydroxide), wonesite (sodium magnesium aluminum silicate hydroxide), andmixtures thereof.

Useful calcium carbonates include finely ground calcium carbonate.Commercially available forms are available from Harwick Chemical, J. M.Huber Corporation, Georgia Marble, Genstar Stone Products and Omya, Inc.

Useful homogenizing agents include those composed of a mixture of lightcolored resins having a specific gravity of about 1.0 g/cc at 23° C. anda softening point of about 100° C. One particularly suitablehomogenizing agent is available in flake form from Struktol Corporationunder the tradename Struktol® 60 NS.

Alumina trihydrates include finely divided, odorless, crystalline, whitepowders having the chemical formula Al₂O₃.3H₂O. Alumina Trihydrate canbe utilized in the present invention to enhance the green strength ofthe base polymer. Useful alumina trihydrates have an average particlesize ranging from about 0.1 micron to about 5 microns, and morepreferably, from about 0.5 micron to about 2.5 microns.

Alumina trihydrate is commercially available from Franklin IndustrialMaterials, of Dalton, Ga. Notably, alumina trihydrate can also beadvantageously used separately as a flame retardant and smokesuppressant in the EPDM-based roofing membrane composition of thepresent invention.

Other sources of alumina trihydrate are available from J. M. HuberCorporation of Norcross, Ga. under the trademark Micral®. These aluminatrihydrates have a median particle size of about 1.1 microns to about1.5 microns, a specific gravity of about 2.42, an ash content of about64-65 weight percent and a loss on ignition at 1000° F. of about 34.65percent by weight.

Still another useful non-combustible mineral filler suitable for thepresent invention is the ore of calcium borate. This filler is availablein various particle size grades from American Borate Company, VirginiaBeach, Va., under the tradename Colemanite® and has the chemical formulaCa₂B₆O₁₁.5H₂O. Colemanite® has a specific gravity of about 2.4.Colemanite® may have an average particle size of about 0.1 to about 5microns, or from about 0.5 to about 2.5 microns.

Yet another flame-retardant mineral filler which may be particularlysuitable for use in the roofing membrane of the present invention ismagnesium hydroxide. Useful magnesium hydroxides (Mg(OH)₂) includefinely divided, white powders that are extremely effective smokesuppressants as well as a flame-retardant additives.

In one or more embodiments, the polymeric membranes of this inventioninclude at least about 20%, in other embodiments at least 25%, and inother embodiments at least about 30% by weight olefinic rubber based onthe entire weight of the membrane. In one or more embodiments, thepolymeric membranes of this invention include less than 100%, in otherembodiments, less than 50%, and in other embodiments less than about 40%by weight olefinic rubber based on the entire weight of the membrane. Itwill be appreciated that by the term “membrane” as used throughout mayrefer to the entire membrane, in the case of a mono-layer membrane, orto the non-black layer of a multi-layered membrane.

In one or more embodiments, the total content of the fillers used in theproduction of the membranes are less than 250 parts by weight mineralfiller per 100 parts by weight rubber. It will be understood that partsby weight of the component per 100 parts by weight of the rubber (e.g.,elastomeric copolymer) can be referred to as phr. It will also beappreciated that reference to the level or amount of filler in thevulcanizable composition corresponds to the level or amount of filler inthe non-black membrane or non-black layer or the membrane. In otherembodiments less than 220 phr, in other embodiments less than 200 phr,and in other embodiments less than 180 phr filler may be included in themembranes. In one or more embodiments, the vulcanizable compositions(and non-black layers of the membranes) include more than 130 phr, inother embodiments more than 140 phr, and in other embodiments more than150 phr of the filler. Inasmuch as the ingredients of the vulcanizablecomposition of matter are employed to make a non-black membrane (orlayer thereof), the fillers employed are non-black.

In one or more embodiments, at least a threshold amount of the fillerincluded in the vulcanizable composition is a non-black reinforcingfiller. In one or more embodiments, at least 25% by weight, in otherembodiments at least 35% by weight, in other embodiments at least 45% byweight of the filler is a non-black reinforcing filler.

In one or more embodiments, silica is employed as a reinforcingnon-black filler. It will be appreciated that silica filler can providethe entire content of the fillers for the polymeric membrane. In one ormore other embodiments, the filler content can include silica filler andtitanium dioxide. In one or more other embodiments, the total fillercontent can include silica filler, titanium dioxide and talc. In one ormore embodiments, titanium dioxide is considered non-reinforcing filler.

In one or more embodiments, the vulcanizable compositions include atleast 15 phr, in other embodiments at least 20 phr, in other embodimentsat least 20 phr, and in other embodiments at least 25 phr of silicafiller. In one or more embodiments, the vulcanizable compositions mayinclude less than 250 phr, in other embodiments, less than 200 phr, inother embodiments less than 90 phr, and in other embodiments less than80 phr silica filler.

In one or more embodiments, the vulcanizable composition of thisinvention include at least 20 phr, in other embodiments at least 25 phr,in other embodiments at least 35 phr, in other embodiments at least 45phr, and in other embodiments at least 55 phr titanium dioxide. In oneor more embodiments, the vulcanizable composition may include less than90 phr, in other embodiments less than 80 phr, in other embodiments lessthan 75 phr, in other embodiments less than 60 phr, and in otherembodiments at least 65 phr titanium dioxide.

In one or more embodiments, the vulcanizable composition of thisinvention are devoid of talc. In one or more embodiments, thevulcanizable composition of this invention include at least 5 phr and inother embodiments at least 15 phr talc. In one or more embodiments, thevulcanizable composition may include less than 90 phr and in otherembodiments less than 50 phr talc.

In certain embodiments, the vulcanizable composition is devoid of mica.In other embodiments, the vulcanizable composition of the invention mayinclude at least 6 phr and in other embodiments at least 12 phr mica. Inone or more embodiments, the vulcanizable composition may include lessthan 25 phr and in other embodiments less than 12 phr mica.

In certain embodiments, the vulcanizable composition includes limitedclay. In particular embodiments, the vulcanizable composition is devoidof clay. In one or more embodiments, the vulcanizable compositionincludes less than 15 phr, in other embodiments less than 10 phr, inother embodiments less than 5 phr, and in other embodiments less than 1phr clay.

In certain embodiments, the vulcanizable composition is devoid ofcalcium carbonate. In other embodiments, the vulcanizable compositionsof the invention may include at least 3 phr and in other embodiments atleast 5 phr calcium carbonate. In one or more embodiments thevulcanizable composition may include less than 200 phr and in otherembodiments less than 20 phr calcium carbonate.

In one or more embodiments, the vulcanizable composition includes fromabout 0.1 phr to about 5 phr, silane coupling agent. In otherembodiments the composition may include at least 0.1 phr, in otherembodiments at least 0.3 phr, in other embodiments at least 0.5 phr, inother embodiments at least 0.7 phr, in other embodiments at least 1 phr,and in other embodiments at least 1.5 phr silane coupling agent. In oneor more embodiments the composition may include less than 5 phr, inother embodiments less than 3 phr, in other embodiments less than 2.5phr, in other embodiments less than 2.0 phr, in other embodiments lessthan 1.8 phr, and in other embodiments less than 1.5 phr silane couplingagent. It should be appreciated that reference to silane coupling agentrefers to the active constituents or portion of any blend or masterbatchincluding a silane coupling agent. For example, one can employ acoupling agent that is included in a blend with an inert carrier (suchas an olefin wax). The activity (i.e. the % of the mixture that includesthe silane coupling agent) may vary, but those skilled in the art willbe able to readily determine the appropriate amount in view of thisdisclosure and the activity of the mixture.

In one or more embodiments, the polymeric membranes of this inventioninclude at least 30 phr, in other embodiments at least 40 phr, and inother embodiments at least 50 phr processing oil. In one or moreembodiments, the membrane of the invention may include less than 120phr, and in other embodiments less than 100 phr, and in otherembodiments less than 50 phr processing oil.

In one or more embodiments, the membranes of this invention includesfrom about 2 to about 10 phr homogenizing agent. In other embodiments,the membrane includes less than 5 phr homogenizing agent, and in otherembodiments less than 3 phr homogenizing agent. In certain embodiments,the vulcanizable composition is devoid of a homogenizing agent.

In one or more embodiments, the vulcanizable composition of thisinvention includes from about 10 to about 65 phr flame retardantpackage. In other embodiments, the vulcanizable composition includesless than 10 phr flame retardant package, and in other embodiments lessthan 5 phr flame retardant package. In certain embodiments, thevulcanizable composition is devoid of a flame retardant package.

The roofing membrane of the present invention can be prepared byconventional means using conventional rubber compounding equipment suchas Brabender, Banbury, Sigma-blade mixer, two-roll mill, or other mixerssuitable for forming viscous, relatively uniform admixtures. Mixingtechniques depend on a variety of factors such as the specific types ofpolymers used, and the fillers, processing oils, waxes and otheringredients used. In one or more embodiments, the ingredients can beadded together in a single shot. In other embodiments, some of theingredients such as fillers, oils, etc. can first be loaded followed bythe polymer. In other embodiments, a more conventional manner can beemployed where the polymer is added first followed by the otheringredients.

Mixing times generally range from about 2 to 6 minutes. In certainembodiments an incremental procedure can be used whereby the basepolymer and part of the fillers are added first with little or noprocess oil, the remaining fillers and process oil are added inadditional increments. In other embodiments, part of the EPDM can beadded on top of the fillers, plasticizers, etc. This procedure can befurther modified by withholding part of the process oil, and then addingit later. In one or more embodiments, two-stage mixing can be employed.

The sulfur cure package (sulfur/accelerator) can be added near the endof the mixing cycle and at lower temperatures to prevent prematurecrosslinking of the EPDM polymer chains. When utilizing a type B Banburyinternal mixer, the dry or powdery materials such as non-black mineralfillers (i.e., untreated clay, treated clays, talc, mica, and the like)can be added first, followed by the liquid process oil and finally thepolymer (this type of mixing can be referred to as an upside-down mixingtechnique).

The silica coupling agent can be added with the fillers near thebeginning of the mixing cycle. In one or more embodiments, the silanecoupling agent is included before the sulfur cure package is added.

Once mixed, the rubber composition can then be formed into a sheet viacalendering. The compositions of the invention can also be formed intovarious types of articles using other techniques such as extrusion.

The resultant rubbery compositions may be prepared in sheet form in anyknown manner such as by calendering or extrusion. The cured sheets mayalso be cut to the desired dimensions. In one or more embodiments, theresulting admixture can be sheeted to thicknesses ranging from 5 to 200mils, in other embodiments from 35 to 90 mils, by using conventionalsheeting methods, for example, milling, calendering or extrusion. In oneor more embodiments, the non-black admixture is sheeted to the desiredthickness and then bonded to a black sheeting material havingessentially the same characteristics as the non-black sheeting materialof the present invention using conventional processing techniques.Typically, the plies are calendered separately and then laminatedtogether in an uncured state, to be dusted and cured in an autoclave orby other means. The sheeting can be visually inspected and cut to thedesired length and width dimensions after curing.

The calendered sheeting itself should show good, uniform release fromthe upper and lower calender rolls and have a smooth surface appearance(substantially free of bubbles, voids, fish eyes, tear drops, etc.). Itshould also have uniform release from the suction (vacuum) cups at thesplicing table and uniform surface dusting at the dust box.

As is known in the art, the uncured polymeric sheets (which may also bereferred to as uncured sheets) can be subjected to heat in order toeffect vulcanization of the rubber. It is believed that this step ofheating promotes the formation of chemical crosslinks between the EPDMpolymer and the silica filler. As is known in the art, the dusted sheetsare wound onto a metal curing mandrel and placed into an autoclave forcuring.

In one or more embodiments, the rubber formulations disclosed herein forfabricating membranes are employed in the manufacture of bilaminatemembranes wherein the non-black rubber formulations are employed toproduce at least one layer of the laminate membranes. In particularembodiments, the non-black formulations disclosed herein are employed toprepare a first layer, and the second layer can derive from a distinctrubber formulation. In one or more embodiments, the distinct rubberformulation (i.e. the rubber formulation employed to prepare the secondlayer) includes carbon black. Rubber formulations that includeelastomeric copolymer and carbon black are generally known in the art asdisclosed in U.S. Pat. Nos. 6,632,509, 6,615,892, 5,700,538, 5,703,154,5,804,661, 5,854,327, 5,093,206, and 5,468,550 which are incorporatedherein by reference. For example, these black formulations may includeelastomeric olefinic copolymer (i.e. rubber), from about 30 to about 160parts by weight carbon black per 100 parts by weight rubber, 40 to 100parts by weight oil per 100 parts by weight rubber, and otheringredients such as a cure package, antioxidants, cure activators, andthe like. As is known in the art, the carbon black can be replaced orsupplemented with other non-black fillers such as clay and talc.

In one or more embodiments, the laminate membranes of the presentinvention are bilaminates wherein each layer of the membrane accountsfor about 50% of the total thickness of the membrane. For example, a 60mil membrane may include a 30 mil first non-black layer and a 30 milsecond carbon black-filled layer. In other embodiments, the thickness ofthe layers can be different. In fact, it may be advantageous toconstruct a membrane with a non-black layer that is thinner than thecarbon black-filled layer. In one or more embodiments, the thickness ofthe non-black layer to the carbon black-filled layer may be about 1:3 toabout 1:1, in other embodiments from about 1:2.5 to about 1:1.5, or inother embodiments from about 1:2 to about 1:1.8.

The membranes of the present invention can be optionally reinforced witha scrim fabric. In other embodiments, the membranes are devoid of scrimfabric.

The roof sheeting membranes can be evaluated for physical propertiesusing test methods developed for mechanical rubber goods. Typicalproperties include, among others, tensile strength, modulus, ultimateelongation, tear resistance, ozone resistance, water absorption,dimensional stability, burn resistivity, and cured compound hardness.

The membranes of this invention can be used as follows. The non-blacklayer can face upward so as to reflect sunlight, and the black layershould face downward toward the building. As the sheet is unrolled overthe roof substructure in a conventional fashion, field seams areprepared by overlapping the edges of a rubber sheet with the edges of anadjacent rubber sheet. The width of the seam can vary depending on therequirements specified by the architect, building contractor, or roofingcontractor and thus, do not constitute a limitation of the presentinvention. Seams can be joined with conventional adhesives such as, forinstance, a butyl-based lap splice adhesive, which is commerciallyavailable from Firestone Building Products Company as SA-1065.Application can be facilitated by spray, brush, swab or other meansknown in the art.

Also, field seams can be formed by using a seam tape and a companionprimer such as QuickSeam™ tape and Quick Prime Plus™ primer, both ofwhich are commercially available from Firestone Building ProductsCompany of Indianapolis, Ind.

Thus it should be evident that the sheeting material and method of thepresent invention are highly effective in covering the roof of abuilding. The invention is particularly suited for use on roofs ofbuildings, but is not necessarily limited thereto. The sheeting materialof the present invention can be used separately with other equipment,methods and the like, such as, for example, for linings for fish ponds,decorative and aquatic gardens, ponds on golf courses, and the like.

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention.Accordingly, for an appreciation of the true scope and breadth of theinvention, reference should be made to the following claims.

Examples Samples 1-3

The following examples are submitted for the purpose of furtherillustrating the nature of the present invention and are not to beconsidered as a limitation of the scope thereof. The parts of eachcompounding ingredient are shown as parts per 100 parts elastomericolefinic terpolymer.

Three non-black rubber roofing membrane compounds were preparedaccording to the recipe in Table I. The compounds were prepared by thecompounding of the elastomers, fillers, processing materials, and otheradditives in a Brabender internal mixer, and resheeted to the desireddimensions using a 88° C. two-roll laboratory mill as describedhereinabove.

TABLE I Sample Nos 1 2 3 Masterbatch EPDM polymer 100 100 100 Silica51.20 51.20 51.20 Titanium dioxide 58.20 58.20 58.20 Mistron Vapor Talc40.60 40.60 40.60 Process Oil (clear) 59.42 59.42 59.42 BlockedMercaptosilane 2.3 (50% active) Unblocked Mercaptosilane 1.15 (100%active) Carbowax 3350 1.99 1.99 1.99 Aflux PE 12 5.01 5.01 5.01 Zincoxide 5.01 5.01 5.01 Stearic Acid 2.50 2.50 2.50 Final Mix 323.93 325.08326.23 Sulfur 0.97 0.97 0.97 Zinc DBDC (Butazate) 1.46 1.46 1.46 MBTS0.30 0.30 0.30 Stearic Acid 0.75 0.75 0.75 Total PHR 327.41 328.56329.71

The various physical properties tested are reported in Table II.

TABLE II Compound Nos. 1 2 3 Mooney Viscosity, Mu 31 33 27 Scorch timet5, minute 20 8 19 100% Modulus, psi 207 302 285 300% Modulus, psi 337633 549 Tensile strength, psi 1535 2445 2177 Elongation at break, % 714698 706 Die C tear, lb/in 149 192 177

For testing purposes, uncured compounds were tested in a MDR 2000machine for their processing properties. The uncured compounds werecured using an electric heated curing press for 45 minutes at 160° C.Cured rubber slabs were die-cut and tested according to ASTM D4637.Mechanical properties were conducted according to ASTM D411.

Samples 4-13

Ten additional non-black rubber roofing membrane compounds were preparedin accordance with the procedure set forth in Samples 1-3 using therecipes set forth in Table III. The results of testing performed on thecompounds or cured sheet thereof are set forth in Table IV.

TABLE III Sample Nos. 4 5 6 7 8 9 10 11 12 13 Ingredients EPDM 51.2 51.251.2 51.2 51.2 51.2 — — — — Silica UltraSid VN2 GR — — — — — — 51.2051.20 51.20 VP Coupsil 64111 — — — — — — — — — 51.20 TiO2 58.20 58.2058.20 58.20 58.20 58.20 58.20 58.20 58.20 58.20 Talc 40.60 40.60 40.6040.60 40.60 40.60 40.60 40.60 40.60 40.60 White Oil 59.42 59.42 59.4259.42 59.42 59.42 59.42 59.42 59.42 59.42 Coupling Agent Deolink MXSilane (50% active) — 2.00 — — — — — — — — Silquest A189 Silane (liquid)— — 1.00 — — — — — — — Si-69 (clear liquid) — — — 1.00 — — — — — —Si-264 (light yellow liquid) — — — — 1.00 — — — — — NXT Z 45 (clearliquid) — — — — 1.00 — 1.00 — — Paraffinic Wax 1.99 1.99 1.99 1.99 1.991.99 1.99 1.99 1.99 1.99 PE Wax 5.01 5.01 5.01 5.01 5.01 5.01 5.01 5.015.01 5.01 Stearic Acid 2.50 2.50 2.50 2.50 2.50 2.50 2.50 2.50 2.50 2.50Sulfur 0.97 0.97 0.97 0.97 0.97 0.97 0.97 0.97 0.97 0.97 Zinc DBDC(Butazate) 1.46 1.46 1.46 1.46 1.46 1.46 1.46 1.46 1.46 1.46 MBTS 0.300.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 Stearic Acid 0.75 0.75 0.750.75 0.75 0.75 0.75 0.75 0.75 0.75 Final Batch Total 327.41 329.41328.41 328.41 328.41 328.41 327.41 325.41 329.41 327.41

TABLE IV Sample Nos 4 5 6 7 8 9 10 11 12 13 Mooney Scorch PW MX A189 69264 NXT PW NXT MX PW Minimum Viscosity 33.70 29.60 34.00 30.70 31.4031.50 33.70 31.10 29.30 26.50 T5 Minutes 12.85 11.13 7.11 9.54 8.43 6.3516.31 6.71 12.60 5.83 T35 Minutes 18.87 16.39 17.75 16.67 15.44 12.0322.87 11.82 18.05 9.19 ASTM D412 Tensile Unaged 100% Modulus, psi 192.5252.2 274.6 259.5 286.8 278.9 207.7 287.8 277.9 327.0 200% Modulus, psi250.6 350.5 401.0 379.1 412.5 402.5 263.9 402.0 379.2 490.8 300%Modulus, psi 313.0 453.3 531.6 496.2 542.7 539.8 321.1 528.8 489.8 677.6500% Modulus, psi 537.1 789.7 935.8 884.1 956.8 986.6 544.6 980.3 872.71323.1 Tensile Strength, psi 1773.6 2172.5 2251.8 2181.4 2196.5 2275.91729.6 2129.6 1867.4 2095.3 Elongation (%) 930.0 904.0 861.0 854.0 846.0825.0 948.0 786.0 786.0 669.0 Total Sample Rupture None All All All AllAll None All All All ASTM D412 Tensile Aged 7 Days @ 240° F. 100%Modulus, psi 378.8 438.2 434.6 469.8 457.0 432.7 390.1 442.0 438.0 438.7200% Modulus, psi 543.9 654.9 678.6 721.0 691.8 653.8 542.8 660.3 635.7673.9 300% Modulus, psi 718.2 912.7 964.0 1004.1 967.2 924.0 709.5 934.3879.6 967.1 500% Modulus, psi 1393.0 1895.4 2008.1 2054.6 1992.9 1926.51384.4 1937.6 1747.6 1969.5 Tensile Strength, psi 2218.9 2373.5 2462.32189.5 2334.2 2189.3 1944.8 2214.0 1835.7 1887.7 Elongation (%) 646.0563.0 562.0 519.0 551.0 539.0 605.0 545.0 514.0 481.0 Total SampleRupture All All All All All All All All All All

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

1-25. (canceled)
 26. A roofing membrane comprising: i. a non-blackelement including silica dispersed within a crosslinked network ofethylene-propylene-diene rubber, where the silica is chemically coupledto the crosslinked network through a reaction with a coupling agentdefined by the formula:

where R⁸ is a divalent organic group or a bond, R⁹ is a halogen atom oran alkoxy group, and each R¹⁰ is independently a halogen, an alkoxygroup, or a monovalent organic group, and where R¹¹ is a blocking group.27. The membrane of claim 26, where the non-black element includes atleast 15 and less than 250 parts by weight silica per 100 parts byweight rubber.
 28. The membrane of claim 26, where the non-black elementincludes at least 20 and less than 200 parts by weight silica per 100parts by weight rubber.
 29. The membrane of claim 26, where thenon-black element further includes titanium dioxide per 100 parts byweight rubber.
 30. The membrane of claim 29, where the non-black elementincludes at least 20 and less than 90 parts by weight titanium dioxideper 100 parts by weight rubber.
 31. The membrane of claim 26, where thenon-black element further includes a processing oil.
 32. The membrane ofclaim 31, where the non-black element includes at least 30 and less than120 parts by weight processing oil per 100 parts by weight rubber. 32.The membrane of claim 32, where the processing oil is a white oil. 33.The membrane of claim 31, where the processing oil has a sulfur contentof less than 0.5 weight percent and an unsaturation level of less than3%.
 34. The membrane of claim 26, where the coupling agent is athioester, a thiophosphinate, a thiophosphate, or a thiosulphonate. 34.A method for preparing a roofing membrane, the method comprising: i.mixing ethylene-propylene-diene rubber, silica, and a coupling agentdefined by the formula:

where R⁸ is a divalent organic group or a bond, R⁹ is a halogen atom oran alkoxy group, and each R¹⁰ is independently a halogen, an alkoxygroup, or a monovalent organic group, and where R¹¹ is a blocking groupto form a mixture; ii. adding a curative to the mixture to form avulcanizable rubber composition; iii. fabricating the vulcanizablecomposition into an uncured sheet; and iv. curing the uncured sheet. 35.The process of claim 34, further comprising the step of introducingethylene-propylene-diene rubber with a coupling agent, where thecoupling agent is dispersed in a carrier.
 36. The process of claim 34,where the curative is sulfur or a sulfur-containing compound.
 37. Theprocess of claim 34, further comprising the step of adding a cureaccelerator.
 38. The process of claim 34, where the coupling agent is athioester, a thiophosphinate, a thiophosphate, or a thiosulphonate.